Condensation sensor

[Detailed Description of the Invention]

Field of the Invention The present invention relates to a dew condensation sensor. PRIOR ART In recent years, the spread of videotape recorders is remarkable, and is in the tendency of year * Miniaturization. And a small thing is desired also about the dew condensation sensor for swivel head cylinders carried in these videotape recorders. On a ceramic substrate, a pair of electrodes use thick film printing technique, the conventional dew condensation sensor is formed, and the moisture-sensitive resistor layer is further formed between this electrode (JP,61-33374,B). The problem which an invention tends to solve Since this dew condensation sensor is what is produced by the screen-stenciling method, that miniaturization is also restrained by the pattern of the screen. However, since there is a limit also in minute-ization of the pattern of a screen, there is a limit also in the miniaturization. The present invention tends to provide a very small sensor compared with an old dew condensation sensor. The means for solving a problem The dew condensation sensor of the present invention forms in one a moisture-sensitive resistor layer and the detection circuit connected to it on a semiconductor substrate. OPERATION Since the moisture-sensitive resistor layer and the detection circuit are formed in one on a semiconductor substrate, it can use semiconductor production technology and it not only can miniaturize a dew condensation sensor, but becomes easy [ the mass production ]. EXAMPLE Hereinafter, one example of the present invention is described using Drawing 1 and Drawing 2. In the figure, 1 is a semiconductor substrate, for example, a silicon substrate, into oxygen environment, at the temperature of 1100 degreeC, it is heated for 2 hours, and oxidizes, and silicon oxide film 2 is formed on the surface. 3 is a polycrystalline silicon layer and is formed by the vapor-depositing method on silicon oxide film 2. A detection circuit part injects impurities into portion 4 surrounded by the dashed dotted line of polycrystalline silicon layer 3 by ion implantation, and is formed in it by wiring. 5 and 6 are electrodes, and on the extension portion of polycrystalline silicon layer 3 from a detection circuit part, sequent deposition of Ti, Pt, and the Au is carried out, and they are laminated and formed. As for the thickness of these electrodes 5.6, about 40 um(s) and the electrode width of about 0.8 micrometer and inter electrode distance are about 10 micrometers. 7 is a Passivation film and is formed by the chemicals gaseous phase vapor-depositing (CVD) method on other portions except electrodes 5 and 6 and the peripheral part of those. On this Passivation film 7, a coupling agent is applied and it is printed. 8 is a moisture-sensitive resistor layer about 3 micrometers thick, and is this, Strip artist bull coat material is applied by the screen-stenciling method on other portions except electrodes 5 and 6 and the peripheral part of those, After carrying out heating solidification and considering it as a film about 20 micrometers thick, the liquefied hygroscopic resin which distributed conductive powder is applied with a spray gun, and after printing for 30 minutes by 160 degreeC, it is formed by exfoliating a strip artist bull coat. 9 is a water-repellent protective film and is formed by applying silicone resin etc. This protective film 9 is a thing for [ which said the water which dewed that surface and arose ] absorbing and making it penetrate to moisture-sensitive resistance layer 8, and prevents that water carries out liquid to moisture-sensitive resistance layer 8 directly. It is prevented from the substance dissolved during dew condensation carrying out invasion contamination, and reducing the characteristic in moisture-sensitive resistance layer 8 by this. In order to produce the dew condensation sensor of this example, it is practical to depend, if a majority of these components are simultaneously formed in the silicon wafer with semiconductor production technology, and it acts as Sklar Eve of the silicon substrate 1 after that, for example, a subdivision rate is carried out to the element of the size of about 2 mmX(s)0.8 pus. Although the silicon substrate is used as a semiconductor substrate in this example, even if it uses other semiconductor substrates (the substrate in which the insulating layer was formed on that surface may be used.) Although the layered product of Ti, Pt, and Au is used for electrodes 5 and 6, the layered product, other metal, for example, the layered product of Ti and Au, which have corrosion resistance, of +Cr and Au, etc. may be used. EFFECT OF THE INVENTION According to the present invention, since it is the structure which formed the moisture-sensitive resistor and the detection circuit in one on the semiconductor substrate, a very small dew condensation sensor can be obtained. And since it is producible with semiconductor production technology, To and-izing from a flea are easy and the reproducibility can not only be good, but can consider it as a cheap thing.

[Brief Description of the Drawings]

The top view of the example of - of the dew condensation sensor which requires Drawing 1 for the present invention, and Drawing 2 are sectional views which met the A-A' line of Drawing 1. 1 ...... silicon substrate, 2 ...... silicon oxide film, 3 ...... polycrystalline silicon layer, 4 ...... detection circuit part, 5.6 ...... electrode, 7 ...... Passivation film in which the coupling agent is given, 8 ...... moisture-sensitive resistor layer.